In recent years, an addition of a new road to road map data is performed by using a vehicle that is equipped with an apparatus for recording new road information instead of using a worker that conduct on-site inspection with reference to a paper map (refer to Japanese Patent Document JP-A-H10-332391). In the technique used in the addition of the new road, the new road information recording apparatus generates information on the new road based on road information input by an occupant of the vehicle, an image around the vehicle captured by a camera or the like.
The road information generated by the above described manner is, for example, handed to a trader that generates and sells road map data (designated as the first tier trader hereinafter), and the first tier trader updates the road map data with the new road information for map data renewal. Then, the road map data updated in the above described manner is further handed to the second tier trader such as a navigation apparatus producer or the like that records the updated road map data in a storage medium such as a hard disk drive (HDD), a digital versatile disk (DVD), a CD-ROM or the like that is intended for a sale to users.
The second tier trader must have the road map data that has a data size to be storable in the storage medium such as the HDD, DVD, CD-ROM or the like due to distribution requirement to the users. Therefore, the second tier trader is required to determine which portion of the updated road map data provided by the first tier trader should be stored in the storage medium for the distribution to the users.
However, the second tier trader is having a hard time for finding out how much of the data size contributes to which of the new roads in the road map data provided by the first tier trader. Therefore, the second tier trader is required to sort out which combination of the new roads fits in the storage medium by trial and error.